Sea-foam which is drifited to the sea shores is a

Options

A. External shell of Cuttle Fish
B. Internal shell of Cuttle Fish
C. Bones of Octopus
D. Calcareous matter excreted by cephalopods.

Answer

To solve the question regarding what sea-foam, which drifts to the sea shores, consists of, we will analyze the options provided and determine which one is correct.

### Step-by-Step Solution:

1. **Understanding Sea-Foam**:
- Sea-foam is formed through the agitation of seawater mixed with organic matter. This organic matter can include dead and decaying marine organisms.

2. **Analyzing the Options**:
- **Option 1: External shell of cuttlefish**:
- Cuttlefish belong to the class Cephalopoda within the phylum Mollusca. They do not have an external shell; instead, they possess an internal shell. Therefore, this option is incorrect.

- **Option 2: Internal shell of cuttlefish**:
- Cuttlefish do have an internal shell, known as the cuttlebone. This internal shell can contribute to the organic matter in the sea, and thus can be part of the sea-foam. This option seems plausible.

- **Option 3: Bones of octopus**:
- Octopuses are also cephalopods and do not have bones. They have a soft body structure, so this option is incorrect.

- **Option 4: Calcareous matter excreted by cephalopods**:
- Cephalopods do not excrete calcareous matter; instead, they excrete nitrogenous waste products like ammonia, urea, or uric acid. Thus, this option is also incorrect.

3. **Conclusion**:
- After analyzing all the options, the only viable answer is **Option 2: Internal shell of cuttlefish**. This is because the internal shell can contribute to the organic matter that forms sea-foam.

### Final Answer:
The correct answer is **Option 2: Internal shell of cuttlefish**.